Ah, you got me beat, I had no idea there was a race or class with a darkvision spec this broken lol, I don't even think a twilight cleric/gloom stalker ranger multiclass would extend the 300 ft range based on the wording of Eyes of Night, but a 390 ft. darkvision does seem like the eyes of god.

when my human rogue is the only one in the party with darkvision

Quote from Sneekking24 >>

Will these work as monicals if cut or separated in half  for 2 people.?

I read somewhere that both lenses have to be worn by the same person to make it work.

But as always, if your DM allows it..

They should include the suggested retail price in the discription

I see where you're coming from (see what I did there?), but it's a magic item. Easy solution is to not give it to any given character until you think it fits where you see them at in their adventuring careers. Considering some races have a base of 120 feet of DV, I have no qualms with a magic item offer 120. 

Drow is 120 + 60 from Goggles = 180

I mean that's something that exists in real life. Basic version is sunglasses, more sophisticated is something like the lense in a welder's mask. I don't think a dm would allow you to just start with that but I'd imagine you could have them commissioned for a fair price, and low level too 

My understanding may be off.  But my understanding is that the warlocks devils sight give you ability to see in darkness (only)  devils sight does NOT give any benefit in dim light. 

210 feet of dark vision moment cause Drow + this + gloomstalker's umbral sight 

mixed with gloomstalker = + 30 feet = 270 feet + warlock devil's sight = + 120 = 390 feet of DV (if DS stacks)

yes

give them 390 cause of devil's sight and your dm is gonna be...angry

I am not sure why people think this is broken.  Darkvision does not give you colored vision as per the definition:

A monster with darkvision can see in the dark within a specific radius. The monster can see in dim light within the radius as if it were bright light, and in darkness as if it were dim light. The monster can't discern color in darkness, only shades of gray. So it is like looking through one of those nightvision cameras.  You can make out images, but not amazing details.  A torch thrown on the ground, or carried is better vision.

Also what battles / exploration are y'all doing that you need / can see more than 60 feet in front of you??

you know that Twilight clerics have 300 ft of darkvision ya?

Our DM put an entire ruined citycenter in a huge cavern beneath our 'hub' city.

Had any of us had 120 ft darkvision, we'd have seen that ambush comming.

Had any of us had 300 ft darkvision, we'd have been doing the ambushing.

It doens't happen often, but it happens.

It would be 180 feet of darkvision as it only extends by 60 feet and never states that it doubles it.

Spelljammer buffed these, since they now let you look at the sun and not be blinded (solar dragon lair)

Up to DM’s discretion if the players try.